1. Field of the Invention
The present invention relates in general to poke-through fire barrier structures and, more particularly, to an improved and novel poke-through fire barrier with knock-out fire barrier openings. Moreover, the invention relates to a novel fire retarding structure including a fire barrier element which is constituted from an intumescent material in the shape of a disc member and is adapted to be installed in a passage or opening formed in a fire-rated floor, and wherein the intumescent disc member incorporates knock-outs for the passage therethrough of insulated conductors or wires.
In the construction of buildings of various types, such as modern office buildings possessing concrete floors, it is frequently necessary to provide fire-rated feed-through fittings for conducting insulated conductors, wires, cables and the like through holes or passages which are formed in the concrete building floor, through the intermediary of which electrical power and other signals such as telecommunication signals may be readily transmitted from a source, for instance, a junction box located at one face of the concrete floor through the opening or passage formed in the floor to a suitable outlet or service head positioned at the opposite face of the floor.
Hereby, in order to accomplish the foregoing purpose, it has generally been customary to insert a feed-through fitting having a poke-through fire barrier into the opening in the concrete floor, pass the insulated conductor or conductors through the fitting and fire barrier from one face of the floor to the other face of the floor, and produce connections with an electrical outlet or service mounted over the opening in the floor, generally the top face of the floor. Although this type of fire-rated transmission of electrical power and telecommunication signals from one floor to another of a building structure, such as a modern office building, is widely employed in the construction industry, difficulties have been encountered in containing fires which are encountered on one floor of the building so as to prevent the fire and heat generated thereby from spreading through the floor passages to the floor located thereabove, with such fires and resultant heat ordinarily being conducted along the insulated wires or conductors and melting the insulation thereof while conducting heat to the upper floor causing the conflagration to rapidly spread.
Currently, in order to counteract problems which have resulted from the propagation of fires from one floor to another of such buildings due to fire and heat being conducted through the openings formed in the fire-rated concrete floors, suitable fire-rated feed-through fittings possessing fire barrier structures have been developed in the technology in which it is intended to provide the fewest possible heat conductive components, and to also incorporate fire-retarding barriers in the floor holes or passages and which, in the presence of fire and heat, will act to effectively form seals about the insulated conductors and concurrently seal the opening or passageway in the concrete floor by essentially expanding so as to inhibit or at least appreciably retard the transmission of heat and fire from one side of the concrete floor to the opposite side thereof, in essence, to the next or upper floor of the building. In order to achieve the foregoing, provision has been made for the installation of suitable fire retarding elements; for example, in the shape of disc members constituted from an expandable fire-retarding material, such as an intumescent material, with holes being preformed therein to permit the conductance therethrough of the insulated conductors, and which elements upon being subjected to fire and heat will rapidly expand so as to seal the floor passage and about the wires or conductors extending through the intumescent disc members.
2. Discussion of the Prior Art
An apparatus for sealing passages through a concrete floor and about an insulated conductor, which provides for disc or plate members consisting of an intumescent material arranged in the passages of a concrete floor is described in Kohaut U.S. Pat. No. 4,099,020. Hereby, in the presence of heat and fire, the plate members of intumescent material expand and essentially seal the passageway. Moreover, a framework or lattice structure of such expandable intumescent material is also provided in the passageway located either below or above the intumescent material plate members so as to further aid in the closing and sealing off of the floor passage in the presence of heat or fire.
Similarly, Castellani, et al. U.S. Pat. No. 4,770,643; Spencer U.S. Pat. No. 4,496,790 and McMarlin U.S. Pat. No. 3,864,883 each disclose different types of poke-through fittings and fire barriers which are employed in passages formed in the concrete floors of building structures, wherein intumescent material is employed to provide a sealing effect about insulated or electrical conductors and to also sealingly contact the walls of the passage upon expansion so as to form a barrier inhibiting or at least retarding the propagation of the fire from one floor to another of the building.
Moreover, Goodsell U.S. Pat. No. 4,336,416, commonly assigned to the assignee of the present invention, and the disclosure of which is incorporated herein by reference, discloses a fire-rated feed-through fitting for transferring insulated wires through a passage formed in a concrete floor of a building structure, such as a multi-storied office building, and in which a plurality of spaced disc members each constituted from an intumescent material is interposed in the passage between electrical junction and outlet boxes located on opposite sides of the floor such that, upon the occurrence of fire and resulting heat at the floor below, the intumescent disc members will expand and seal the insulated conductors and the passage to inhibit or retard the spread of fire therethrough to the upper floor. In connection with the structure disclosed in this patent, a plurality of such fire barriers may be spaced within the length of the passage in the concrete floor to enable the arrangement of a plurality of heat sinks to lower the temperature from the encountered fire at the level of the upper floor, thereby reducing the propagation of heat and fire through the floor passage.
Although the foregoing installations of fire-rated fittings with poke-through fire barriers, the latter of which are ordinarily made from intumescent materials in disc or plate-like shapes having preformed openings therein to allow conductors or wires to extend through, with the openings being made as small as possible such that the intumescent material upon expansion thereof in response to the heat from a fire, can seal around the insulated wires even while the insulation thereof is burning and melting off, the current need for ever larger cables or numbers of cables being conducted through such poke-through fittings necessitate the formation of larger preformed openings in the fire barriers. Consequently, this has necessitated the installation of auxiliary fire-barrier material in the form of rigid pieces of intumescent material or as a putty which intumesces in the floor passage when exposed to heat and/or fire so as to produce a sealing effect. The installation of such auxiliary fire barriers to prevent the propagation of heat or fire through the floor passage, in view of the presence of large preformed openings in the fire barriers which are constituted from intumescent material plates or disc members, is quite difficult to handle by an electrician or possibly inadequately skilled personnel, and may not be properly installed as required and specified by the manufacturer. Consequently, the fire barrier material if not properly installed may fail to seal off the floor passage at the occurrence of a fire in the absence of proper installation of such auxiliary fire barrier material. This may subject the installer and the manufacturer to legal liabilities in the event of damage being sustained as a result of fire spreading through such passages and improperly installed poke-through fire barriers in building structures.